1. Field
Embodiments relate to a washing machine which performs a tub cleaning course using a sensor to sense vibration of a tub, and a control method thereof.
2. Description of the Related Art
In general, a washing machine (usually, a drum washing machine) is an apparatus, which includes a tub to contain water (wash water or rinse water), a cylindrical drum rotatably installed to receive laundry, and a motor generating driving force to rotate the drum, and achieves washing of the laundry through tumbling of the laundry along the inner wall of the drum when the cylindrical drum is rotated.
Such a washing machine performs washing of laundry through a series of cycles, i.e., a washing cycle to remove contaminants from the laundry using water dissolving a detergent (concretely, wash water), a rinsing cycle to remove foams and residues of the detergent from the laundry using water not dissolving the detergent (concretely, rinse water), and a spin-drying cycle to dehydrate the laundry at a high speed. When the laundry is washed through this series of cycles, contaminants or lime scales are deposited on the rear surface of the drum as time goes by. The contaminants or the lime scales cause propagation of microorganisms (bacteria) throughout the tub, and further generate surface deposits (flock) causing decay, thereby bringing about generation of mold. The mold is a source of odor generation due to metabolic products thereof, or is attached to laundry while subsequent washing of laundry is performed, thus contaminating the laundry.
In order to solve this problem, a tub cleaning course, in which water is supplied to the washing machine, the supplied water is heated to a set sterilization temperature (a temperature to sterilize microorganisms) by a heater and simultaneously, the drum is agitated so as to sufficiently sterilize and wash the overall of the tub using hot water and steam, is carried out. In order to perform the tub cleaning course, whether or not laundry is present in the drum is sensed before or while the tub cleaning course is performed.
Therefore, the conventional washing machine proposes various methods to sense whether or not laundry is present in the drum.
In one example, a degree of inertia of the laundry in the drum is predicted. Whether or not laundry is present in the drum is sensed by accelerating the drum by applying a designated voltage to the motor and then predicting inertia using the voltage and the velocity variation of the motor during acceleration. This method in which whether or not laundry is present in the drum is sensed by predicting the degree of inertia of the laundry does not require an additional sensor and thus is advantageous in terms of material costs, but causes a high possibility in generating an error in sensing of the laundry according to voltages and generates a deviation according to washing machine models.
In another example, whether or not laundry is present in the drum is sensed using a vibration switch sensing vibration of the tub generated due to disposition of the laundry in the drum to one side. This method in which whether or not laundry is present in the drum is sensed using the vibration switch generates noise or vibration if unbalance of the laundry is generated due to rotation of the drum at a high speed, and, if it is severe, enables sensing as to whether or not laundry is present in the drum only when excessive vibration, such as set movement or frame touch, is generated, thereby being in capable of sensing whether or not laundry is present in the drum in real time.
Further, in order to sense whether or not laundry is present in the drum, sensing of the weight or the unbalance of the drum after water supply is required, thereby causing consumption of separate time, water, and energy.